1. Field of the Invention
The present invention relates to a dual band antenna. More particularly, the present invention relates to a dual band antenna covering both digital TV (DTV) and industrial, scientific and medical (ISM) bands.
2. Description of Related Art
After years of research and development, a DTV now may be a hand-held device, and a computer or a notebook computer may also receive DTV signals via a suitable receiving interface. As to a communication product, design of an antenna is essential, since the quality of the antenna design affects the quality of communication. For example, the antennas include external antennas and embedded antennas, the external antenna includes monopole antenna, dipole antenna and helix antenna etc., and the embedded antenna includes planar inverted F antenna (PIFA) and microstrip antenna.
Due to diversified requirement in wireless transmission and wireless communication, an electronic device is generally required to support different wireless transmission interfaces and different transmission bands. When signals of different bands, such as the ISM band of 2.4 GHz˜2.3835 GHz and the aforementioned DTV band (for example 469 MHz˜882 MHz, which may be different in different countries) are required to be integrated within the electronic device, a general solution is to set different antennas for receiving the signals with different bands. However, since the hand-held electronic device requires features of light-weighted and slim, setting of a plurality of antenna groups not only increases a cost of the electronic device, but also increases a size of the electronic device, which is of no avail to the design of the electronic device.